1. Field of the Invention
The present invention relates to an interface card for a medium (a small storage medium) which is inserted into a slot of an information processing device while holding the medium therein so as to allow for data transmission between the medium and the information processing device, which may be a personal computer or other processing device.
2. Description of Related Art
Interface cards which can be inserted into PC card slots of personal computers while holding media therein have been developed. The interface cards allow data stored in the media while being used in digital cameras, digital video cameras, mobile telephones and other apparatuses, to be used in information processing devices, such as personal computers.
FIG. 10 shows data transmission between an information processing device 62 and a medium (for example, compact flash™) 64 when a conventional interface card 60 is inserted in the information processing device 62. Both the data transmission and data input/output to/from the medium 64 are performed by data buses with a 16-bit width, and consequently, the data transmission between the information processing device 62 and the medium 64 is performed entirely by data buses with a 16-bit width. The data input/output speed to/from the medium 64 can be higher than the data transmission speed produced by a data bus with a 16-bit width. However, when the information processing device 62 and the medium 64 are connected to each other via data buses with a 16-bit width, it is impossible to perform higher-speed data transmission than the data transmission speed by use of data buses with a 16-bit width.
Meanwhile, a card bus mode in which data transmission is carried out via a data bus with a 32-bit width has been developed. When a conventional interface card is inserted in an information processing device which is compatible with the card bus mode, however, if data input/output to/from a medium is carried out via a data bus with a 16-bit width, data transmission between the information processing device and the medium-will be carried out entirely via data buses with a 16-bit width. Thus, even if the information processing device is compatible with the card bus mode, as long as a conventional interface card is used, the information processing device cannot utilize its full transmission performance, and high-speed data transmission between the information processing device and the medium is impossible.
In order to solve the problems described above, the inventors invented an interface card 70 with a memory buffer 76 shown in FIG. 11. A patent application which discloses the interface card 70 was filed in the Japanese Patent Office and assigned Japanese Patent Application No. 2000-294355. When the interface card 70 with the memory buffer 76 is inserted in an information processing device 72, data transmission between the information processing device 72 and the memory buffer 76 is carried out via data buses having a 32-bit width. Also, the data input/output to/from the medium via a data bus with a 16-bit width is carried out at a higher speed. Thus, the interface card 70 permits faster data transmission than the conventional interface card 60.
The interface card 70 shown by FIG. 11 works efficiently in an environment which is compatible with the card bus mode. However, when the information processing device is of an old type which is not compatible with the card bus mode, and even if the information processing device is compatible with the card bus mode, when the operating system is not compatible with the card bus mode, even with the interface card 70, faster data transmission is impossible.
Where various types of information processing devices and various types of operating systems exist, an interface card which is compatible with only one data transmission mode is not able to permit full-speed data transmission between an information processing device and a medium. There may be users which do not know the data transmission mode that is suitable for the environment. Even if users know the suitable data transmission mode, it is inconvenient and costly for users to have different types of interface cards for various types of environment. For these reasons, an interface card which is compatible with different data transmission modes and which can select a data transmission mode that is suitable for the particular environment.
At present, these problems are caused by differences in specifications between a 16-bit-wide data bus mode and a card bus mode and/or variations among information processing devices and operating systems in compatibility with the card bus mode. As new specifications of data buses and new input/output specifications of media are developed and proposed in the future, similar problems will occur.